Illumination apparatus and projection display apparatus

ABSTRACT

An illumination apparatus includes multiple liquid crystal panels, a polarization-state adjusting element, and a cross dichroic prism. A green component light includes a central-wavelength component light, a short-wavelength component light, and a long-wavelength component light. The polarization-state adjusting element separately adjusts a polarization state of the central-wavelength component light and each of polarization states of the long-wavelength component light and the short-wavelength component light.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application No. 2008-206232, filed on Aug. 8,2008; the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an illumination apparatus and aprojection display apparatus that use a red component light, a greencomponent light, and a blue component light.

2. Description of the Related Art

Heretofore, there has been known a projection display apparatus thatincludes: three light valves corresponding respectively to light beamsof three colors; a cross dichroic cube configured to combine light beamsemitted from the three light valves; and projection means configured toproject the light beams combined by the cross dichroic cube.

Here, the cross dichroic cube has: three light-incident surfaces onwhich light beams are incident; and a single light-emitting surface fromwhich light beams are emitted. Accordingly, when light beams of threecolors are to be incident on the cross dichroic cube, the projectiondisplay apparatus needs only a single cross dichroic cube.

Meanwhile, for the purpose of improving color reproducibility andbrightness, there has been proposed a projection display apparatus usinglight beams of four or more colors. For example, the projection displayapparatus has improved color reproducibility and brightness by using,for example, orange, yellow, or cyan in addition to three colors of red,green, and blue (for example, see Japanese Patent ApplicationPublication No. 2002-287247 (Claims 1 and 4, FIG. 1, and the like)).

In this respect, when the projection display apparatus has light beamsof four or more colors, it is impossible to combine the light beams offour or more colors by only a single cross dichroic cube. For thisreason, the projection display apparatus needs to include multipledichroic cubes (or, cross dichroic cubes).

For example, assume a case where light beams of four colors need to becombined with one another. In this case, the projection displayapparatus firstly obtains two combined light beams each by combininglight beams of two colors, and further combines the two combined lightbeams with each other so as to obtain a combined light beam of fourcolors. It should be noted that the projection display apparatus mayobtain a combined light beam of four colors by firstly obtaining acombined light beam of three colors, and then combining the combinedlight beam of three colors with a light beam of a single color.Alternatively, the projection display apparatus may obtain a combinedlight beam of four colors by firstly obtaining a combined light beam oftwo colors, and then combining the combined light beam of two colorswith light beams of two colors.

In this regard, it is necessary that multiple dichroic cubes (or, crossdichroic cubes) be provided between the light valves and the projectionmeans. For this reason, the back focus of the projection means is madelong.

Consequently, the attempt to improve color reproducibility andbrightness results in an increase in cost of the entire projectiondisplay apparatus because the projection means that is employed in theprojection display apparatus using light beams of three colors cannot beutilized for such projection display apparatuses using four or morecolor light beams.

SUMMARY OF THE INVENTION

An illumination apparatus according to a first aspect includes: a lightsource (a light source 10) configured to emit white light; a colorseparator (a dichroic mirror 71 and a dichroic mirror 72) configured toseparate the white light emitted by the light source into a first colorcomponent light having a first wavelength band, a second color componentlight having a second wavelength band, and a third color component lighthaving a third wavelength band; a first light valve (for example, aliquid crystal panel 50R) configured to modulate the first colorcomponent light on the basis of a first input signal; a second lightvalve (or example, a liquid crystal panel 50G) configured to modulatethe second color component light on the basis of a second input signal;a third light valve for example, a liquid crystal panel 50B) configuredto modulate the third color component light on the basis of a thirdinput signal; and a color combiner (a cross dichroic prism 60)configured to combine the first color component light emitted from thefirst light valve, the second color component light emitted from thesecond light valve, and the third color component light emitted from thethird light valve. The illumination apparatus includes apolarization-state adjusting element (a polarization-state adjustingelement 51X) provided on the light-incident-side of the second lightvalve. In the illumination apparatus, the second wavelength band has acentral-wavelength band, a short-wavelength band on the shorterwavelength side than the central-wavelength band, and a long-wavelengthband on the longer wavelength side than the central-wavelength band. Thepolarization-state adjusting element is configured to separately adjusta polarization state of light in the central-wavelength band and apolarization state of light in each of the short-wavelength band and thelong-wavelength band.

According to the first aspect, the polarization-state adjusting elementseparately adjusts the polarization state of light in thecentral-wavelength band and the polarization state of light in each ofthe short-wavelength band and the long-wavelength band. For this reason,a mode with priority given to color reproducibility (a colorreproducibility priority mode) and a mode with priority given tobrightness (a brightness priority mode) can be switched from one to theother.

According to the first aspect, the second color component light emittedfrom the polarization-state adjusting element is incident on the secondlight valve. In other words, three types of light are incident on thecolor combiner. As a result, there is no need to change the design ofthe projection lens unit, thereby suppressing an increase in cost of theentire apparatus.

In the first aspect the long-wavelength band has a wavelength band widerthan that of the short-wavelength band.

In the first aspect, the polarization-state adjusting element is an edgefilter element configured not to adjust the polarization state of lightin the central-wavelength band but to adjust the polarization state oflight in each of the short-wavelength band and the long-wavelength band.

In the first aspect, the polarization-state adjusting element is formedof a combination of: a first notch filter element configured not toadjust the polarization state of light in the central-wavelength bandbut to adjust the polarization state of light in the short-wavelengthband; and a second notch filter element configured not to adjust thepolarization state of light in the central-wavelength band but to adjustthe polarization state of light in the long-wavelength band.

In the first aspect, the second wavelength band includes at least agreen wavelength band.

A projection display apparatus according to a second aspect includes: alight source configured to emit white light; color separators configuredto separate the white light emitted by the light source into a firstcolor component light having a first wavelength band, a second colorcomponent light having a second wavelength band, and a third colorcomponent light having a third wavelength band; a first light valveconfigured to modulate the first color component light on the basis of afirst input signal; a second light valve configured to modulate thesecond color component light on the bas of a second input signal; athird light valve configured to modulate the third color component lighton the basis of a third input signal; a color combiner configured tocombine the first color component light emitted from the first lightvalve, the second color component light emitted from the second lightvalve, and the third color component light emitted from the third lightvalve; and projection means configured to project light emitted from thecolor combiner. The projection display apparatus comprises apolarization-state adjusting element provided on the light-incident-sideof the second light valve. In the projection display apparatus, thesecond wavelength band has a central-wavelength band, a short-wavelengthband on the shorter wavelength side than the central-wavelength band,and a long-wavelength band on the longer wavelength side than thecentral-wavelength band The polarization-state adjusting elementseparately adjusts a polarization state of light in thecentral-wavelength band and a polarization state of light in each of theshort-wavelength band and the long-wavelength band.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a configuration of a projection displayapparatus 100 according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining an illumination apparatus accordingto a conventional technique (1).

FIG. 3 is a diagram for explaining an illumination apparatus accordingto a conventional technique (2).

FIG. 4 is a diagram for explaining an illumination apparatus accordingto the first embodiment.

FIG. 5 is another diagram for explaining the illumination apparatusaccording to the first embodiment.

FIG. 6 is a diagram showing a schematic configuration near apolarization-state adjusting element 51X according to the firstembodiment.

FIGS. 7A and 7B are diagrams each showing the polarization-stateadjusting element 51X according to the first embodiment.

FIG. 8 is a diagram for explaining an edge filter element according tothe first embodiment.

FIG. 9 is a diagram for explaining the function of thepolarization-state adjusting element 51X according to the firstembodiment.

FIG. 10 is a block diagram showing the function of the projectiondisplay apparatus 100 according to the first embodiment.

FIG. 11 is a diagram showing wavelength bands respectively for colorsaccording to the first embodiment.

FIG. 12 is a diagram for explaining color reproduction ranges forillumination apparatuses in a comparative evaluation.

FIG. 13 is a diagram showing a schematic configuration near apolarization-state adjusting element 51X according to a secondembodiment.

FIGS. 14A and 14B are diagrams each for explaining the function of anotch filter element according to the second embodiment.

FIG. 15 is a diagram showing a configuration of a liquid crystal panel50 (particularly, a polarization-state adjusting element 51X and thelike) according to a third embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, projection display apparatuses according to embodiments ofthe present invention will be described with reference to the drawings.Throughout the drawings, the same or similar portions will be denoted bythe same or similar reference symbols.

It should be noted that the drawings are all schematic and thatproportions and the like of dimensions are different from actual ones.Thus, specific dimensions and the like should be determined with thedescription below taken into consideration. Additionally, these drawingsinclude portions where relations or proportions of dimensions aredifferent therebetween.

[First Embodiment]

(Configuration of Projection Display Apparatus)

A configuration of a projection display apparatus according to a firstembodiment of the present invention will be described below withreference to the drawings. FIG. 1 is a diagram showing a configurationof the projection display apparatus 100 according to the firstembodiment.

As shown in FIG. 1, the projection display apparatus 100 includes aprojection lens unit 110, and an illumination apparatus 120. Theprojection display apparatus 100 utilizes a red component light R, agreen component light G, and a blue component light B, which will bedescribed later.

In the first embodiment, the red component light R is a light (a firstcolor component light) having at least a red wavelength band (a firstwavelength band). The green component light G is a light (a second colorcomponent light) having at least a green wavelength band (a secondwavelength band). The blue component light B is a light (third colorcomponent light) having at least a blue wavelength band (a thirdwavelength band).

In the first embodiment, the green wavelength band (the secondwavelength band) includes: a central-wavelength band; a short-wavelengthband located on a shorter wavelength side than the central-wavelengthband; and a long-wavelength band located on the longer wavelength sidethan the central-wavelength band. Hereinafter, light having thecentral-wavelength band will be referred to as a “central-wavelengthcomponent light Gc.” Light having the short-wavelength band will bereferred to as a “short-wavelength component light Gs.” Light having thelong-wavelength band will be referred to as a “long-wavelength componentlight Gl.” Note that, the short-wavelength component light Gs and thelong-wavelength component light Gl will be collectively referred to as a“long/short-wavelength component light LS.”

In the first embodiment, the long-wavelength component light Gl has awavelength band of an intermediate color located on the long-wavelengthside. The intermediate color on the long-wavelength side is a colorhaving a hue between green and red. Specifically, thelong-wavelength-side intermediate color includes a color having a huebetween green and red (for example, yellow and orange).

In the first embodiment, the short-wavelength component light Gs has awavelength band of an intermediate color on the short-wavelength side.The short-wavelength-side intermediate color includes a color having ahue between blue and green (for example, a part of cyan (on thelong-wavelength side)).

The projection lens unit 110 projects image light emitted by theillumination apparatus 120 onto a screen (not illustrated) or the like.

The illumination apparatus 120 includes a light source 10, a UV/IR cutfilter 20, a fly-eye lens unit 30, a PBS array 40, multiple liquidcrystal panels 50 (a liquid crystal panel 50R, a liquid crystal panel50G, and a liquid crystal panel 50B), a polarization-state adjustingelement 51X, a cross dichroic prism 60, a mirror group 70, and a lensgroup 80.

The light source 10 is a UHP lamp or the like, which emits white light.In other words, light emitted by the light source 10 includes the redcomponent light E, the green component light G, and the blue componentlight B. The green component light G includes the central-wavelengthcomponent light Gc, the long-wavelength component light Gl, and theshort-wavelength component light Gs.

The UV/IR cut filter 20 transmits a visible light component (the redcomponent light R, the green component light G, and the blue componentlight B). The UV/IR cut filter 20 shields an infrared light componentand an ultraviolet light component.

The fly-eye lens unit 30 uniformizes light emitted by the light source10. Specifically, the fly-eye lens unit 30 is formed of a fly-eye lens80 a and a fly-eye lens 30 b. Each of the fly-eye lens 30 a and thefly-eye lens 80 b is formed of multiple minute lenses. Each minute lenscollects light emitted by the light source 10 so that the light emittedby the light source 10 can be applied to the entire surfaces of theliquid crystal panels 50.

The Polarized Beam Splitter (PBS) array 40 uniformly converts thepolarization state of light emitted from the fly-eye lens unit 30 into asingle polarization state. For example, the PBS array 40 uniformlyconverts the light emitted from the fly-eye lens unit 80 intoS-polarization (or, P-polarization).

The liquid crystal panel 50R modulates the red component light R byrotating the polarization direction of the red component light R. Alight-incident-side polarizing plate 52R is provided on a side wherelight is incident on the liquid crystal panel 50R. Thelight-incident-side polarizing plate 52R transmits light having onepolarization direction (for example, S-polarization), and shields lighthaving the other polarization direction (for example, P-polarization). Alight-emitting-side polarizing plate 53R is provided on a side wherelight is emitted from the liquid crystal panel 50R. Thelight-emitting-side polarizing plate 53R shields light having onepolarization direction (for example, S-polarization), and transmitslight having the other polarization direction (for example,P-polarization).

The liquid crystal panel 50G modulates the green component light G byrotating a polarization direction of the green component light G. Alight-incident-side polarizing plate 52G is provided on a side wherelight is incident on the liquid crystal panel 50G. Thelight-incident-side polarizing plate 52G transmits light having onepolarization direction (for example, S-polarization), and shields lighthaving the other polarization diction or example, P-polarization).Meanwhile, a light-emitting-side polarizing plate 53G is provided on aside where light is emitted from the liquid crystal panel 50G. Thelight-emitting-side polarizing plate 58G shields light having onepolarization direction (for example, S-polarization), and transmitslight having the other polarization direction (for example,P-polarization). It should be noted that the green component light Gincludes the central-wavelength component light Gc, the long-wavelengthcomponent light Gl, and the short-wavelength component light Gs.

The liquid crystal panel 50B modulates the blue component light B byrotating the polarization direction of the blue component light B. Alight-incident-side polarizing plate 52B is provided on a side wherelight is incident on the liquid crystal panel 50B. Thelight-incident-side polarizing plate 62B transmits light having onepolarization direction (for example, S-polarization), and shields lighthaving the other polarization direction (for example, P-polarization).Meanwhile, a light-emitting-side polarizing plate 53B is provided on aside where light is emitted from the liquid crystal panel 50B. Thelight-emitting-side polarizing plate 53B shields light having onepolarization direction (or example, S-polarization), and transmits lighthaving the other polarization direction (for example, P-polarization).

Here, each of the liquid crystal panels 50 (the liquid crystal panel50R, the liquid crystal panel 50G, and the liquid crystal panel 50B) isprovided with a compensator (not illustrated) so as to improve contrastratio and transmittance. In addition, each of the polarizing plates (alight-incident-side polarizing plate 52R, a light-incident-sidepolarizing plate 52G, a light-incident-side polarizing plate 52B, alight-emitting-side polarizing plate 53R, a light-emitting-sidepolarizing plate 53G, and a light-emitting-side polarizing plate 53B)may include a pre-polarizing plate, which reduces the amount of lightincident on the polarizing plate as well as the heat load thereon.

Preferably, the red component light R and the blue component light Bincident on the cross dichroic prism 60 have the S-polarizations, andthe green component light G incident on the cross dichroic prism 60 hasthe P-polarization. The polarization direction of each component lightdepends on an arrangement of optical elements, and a ½ λ wave plate maybe used for adjusting the polarization direction of the red componentlight R and the blue component light B into the S-polarization.

The polarization-state adjusting element 51X is located between acondenser lens 83G to be described later and the light-incident-sidepolarizing plate 52G, and is provided on an optical path of the greencomponent light G separated by a dichroic mirror 72. Thepolarization-state adjusting element 51X adjusts the polarization stateof the long/short-wavelength component light LS, and thus transmits thegreen component light G. On the other hand, the polarization-stateadjusting element 51X does not adjust the polarization state of thecentral-wavelength component light Gc, and thus transmits the greencomponent light G.

Here, the polarization-state adjusting element 51X is an optical elementconfigured to be capable of selectively making changes between a statewhere the polarization direction of the long/short-wavelength componentlight LS is not adjusted (rotated) and a state where the polarizationdirection of the long/short-wavelength component light LS is adjusted(rotated) by 90°. It should be noted that the polarization-stateadjusting element 51X will be described in detail later (see FIGS. 7 and8).

The cross dichroic prism 60 is a color combiner that combines lightbeams emitted respectively from the liquid crystal panel 50R, the liquidcrystal panel 50G, and the liquid crystal panel 50B. The combined lightcombined by the cross dichroic prism 60 is guided to the projection lensunit 110.

The mirror group 70 includes a dichroic mirror 71, the dichroic mirror72, and reflection mirrors 73 to 76.

The dichroic mirror 71 transmits the blue component light B out of lightemitted from a condenser lens 82, which will be described later. Thedichroic mirror 71 reflects the red component light R and the greencomponent light G out of light emitted from the condenser lens 82.

The dichroic mirror 72 transmits the red component light R out of lightreflected by the dichroic mirror 71. The dichroic mirror 72 reflects thegreen component light G out of light transmitted through the dichroicmirror 71.

The reflection minor 73 reflects light (the red component light R, thegreen component light G, and the blue component light B) emitted from acondenser lens 81, and thus guides the reflected light toward thedichroic mirror 71 and the dichroic mirror 74.

The reflection mirror 74 reflects the blue component light B transmittedthrough the dichroic mirror 71, and thus guides the reflected lighttoward the liquid crystal panel 50B. The reflection mirror 76 reflectsthe red component light R transmitted through the dichroic mirror 72,and thus guides the reflected light toward the reflection mirror 76. Thereflection mirror 76 reflects the red component light R reflected by thereflection mirror 75, and thus guides the reflected light toward theliquid crystal panel 50R.

The lens group 80 includes the condenser lens 81, the condenser lens 82,a condenser lens 88R, the condenser lens 83G, a condenser lens 83B, arelay lens 84, and a relay lens 85.

The condenser lens 81 collects light transmitted through the UV/IR cutfilter 20, the fly-eye lens unit 30, and the PBS array 40. The condenserlens 82 collects light reflected by the reflection mirror 73.

The condenser lens 83R substantially collimates the red component lightR so that the liquid crystal panel 50H should be irradiated with the redcomponent light R. The condenser lens 83G substantially collimates thegreen component light G so that the liquid crystal panel 50G should beirradiated with the green component light G. The condenser lens 83Bsubstantially collimates the blue component light B so that the liquidcrystal panel 50B should be irradiated with the blue component light B.

The relay lens 84 and the relay lens 85 substantially form an image ofthe red component light R on the liquid crystal panel 50R, whilesuppressing an enlargement of the red component light R.

(Difference Between Conventional Technique and Embodiment)

Hereinbelow, the difference between the conventional technique and theembodiment will be described. Specific, a conventional technique (1), aconventional technique (2), and the embodiment will be described in thisorder with reference to FIGS. 2 to 5.

In the following description, a cutoff wavelength of the dichroic mirrorwhich separates the blue component light B and the green component lightG is represented as a “DM1”. In addition, a cutoff wavelength of thedichroic mirror which separates the green component light G and the redcomponent light R is represented as a “DM2”.

Note that, the dichroic mirror separates color component light beam intotwo color component light beams, in accordance with the cutoffwavelength. However, it should be noted that the dichroic mirror is notcapable of completely separating the color component light beam into twocolor component light beams. Therefore, attention should be paid to thefact that, after separation of the color component light beam, oneseparated color component light beam (on the short-wavelength side)includes light with a longer wavelength side than the cutoff wavelength.Similarly, attention should be paid to the fact that, after separationof the color component light beam, the other separated color componentlight beam (on the long-wavelength side) includes light with a shorterwavelength than the cutoff wavelength.

Firstly, an illumination apparatus according to the conventionaltechnique (1) will be described with reference to FIG. 2. Note that theillumination apparatus according to the conventional technique (1) doesnot utilize a yellow component light Ye.

As shown in FIG. 2, the DM1 is provided in a wavelength band of anintermediate color having a hue between blue and green. For example, theDM1 is in a range of 496 nm to 510 nm. The DM2 is provided in awavelength hand of an intermediate color having a hue between green andred. For example, the DM2 is in a range of 585 nm to 600 nm.

Here, the illumination apparatus according to the conventional technique(1) is provided with a cut filter for cutting off the yellow componentlight Ye. Here, a cutoff wavelength of the cut filter is represented as“CF”. The CF is provided in a wavelength band of an intermediate colorhaving a hue between green and red. For example, the CF is in a rage of575 nm to 595 nm. It should be noted here that the cut filter is morecapable of sharply cutting off the yellow component light Ye by usingthe CF as a border than the dichroic mirror.

In should be noted that light having a wavelength band sandwichedbetween the CF and the DM2 is cut off. In FIG. 2, the CF is provided onthe shorter wavelength side than the DM2. Instead, the CF may beprovided on the longer wavelength side than the DM2. In such a case, itis a matter of course that the DM2 is shifted to the short-wavelengthside.

Secondly, an illumination apparatus according to the conventionaltechnique (2) will be described with reference to FIG. 3. Theillumination apparatus according to the conventional technique (2) has:a brightness priority mode with use of the yellow component light Ye;and a color reproducibility priority mode without use of the yellowcomponent light Ye. Note that, in the color reproducibility prioritymode, only light on the long-wavelength side of the green componentlight G is cut off.

As shown in FIG. 3, the DM1 is provided in a wavelength band of anintermediate color having a hue between blue and green. For example, theDM1 is in a range of 495 mm to 510 nm as in the case of the DM1according to the conventional technique (1). The DM2 is provided in awavelength band of an intermediate color having a hue between green andred. For example, the DM2 is in a range of 585 nm to 600 nm.

Here, the illumination apparatus according to the conventional technique(2) is provided with a selective superimposing optical element forselectively cutting off the yellow component light Ye. The selectivesuperimposing optical element transmits the yellow component light Ye inthe brightness priority mode. On the other hand, the selectivesuperimposing optical element cuts off the yellow component light Ye inthe color reproducibility priority mode. When the selectivesuperimposing optical element cuts off the yellow component light Ye inthe color reproducibility priority mode, the cutoff wavelength on theshort-wavelength side is, for example, in a range of 575 nm to 595 nm asin the case of the CP according to the conventional technique (1).

It should be noted here that the selective superimposing optical elementis more capable of sharply cutting off the yellow component light Ye byusing the cutoff wavelength on the short-wavelength side as a borderthan the dichroic mirror.

Thirdly, an illumination apparatus according to the embodiment will bedescribed with reference to FIGS. 4 and 5. The illumination apparatusaccording to the embodiment has; a brightness priority mode with use ofthe long/short-wavelength component light LS; and a colorreproducibility priority mode without use of the long/short-wavelengthcomponent light LS. The long/short-wavelength component light LSincludes the long-wavelength component light Gl and the short-wavelengthcomponent light Gs. Both the long-wavelength component light Gl and theshort-wavelength component light Gs are cut off in the colorreproducibility priority mode. The long-wavelength component light Glmay be correspond to a yellow component light Ye, and theshort-wavelength component light Gs may be correspond to a cyancomponent light Cy.

As shown in FIGS. 4 and 5, the DM1 is provided in a wavelength band ofan intermediate color having a hue between blue and green. The DM1 is,for example, in a range of 495 nm to 510 nm as in the case of the DM1according to the conventional technique (1).

The DM2 is provided in a wavelength band of an intermediate color havinga hue between green and red. The DM2 is, for example, in a range of 590nm to 610 nm. In other words, the DM2 according to the embodiment isprovided on the longer wavelength side than the DM2 according to theconventional technique (1) and the DM2 according to the conventionaltechnique (2). For this reason, it should be noted that the wavelengthband of the long-wavelength component light Gl is wider than thewavelength band of the short-wavelength component light Gs.

Here, the illumination apparatus according to the embodiment is providedwith a polarization-state adjusting element for selectively cutting offthe long/short-wavelength component light LS. In the brightness prioritymode, the polarization-state adjusting element adjusts the polarizationstate of the long/short-wavelength component light LS so that thelong/short-wavelength component light LS should reach the liquid crystalpanel 50G. On the other hand, in the color reproducibility prioritymode, the polarization-state adjusting element adjusts the polarizationstate of the long/short-wavelength component light LS so that thelong/short-wavelength component light LS should not reach the liquidcrystal panel 50G.

When the polarization-state adjusting element cuts off thelong-wavelength component light Gl in the color reproducibility prioritymode, the cutoff wavelength on the short-wavelength side is, forexample, in a range of 575 nm to 596 nm as in the case of the CFaccording to the conventional technique (1). When the polarization-stateadjusting element cuts off the short-wavelength component light Gs inthe color reproducibility priority mode, the cutoff wavelength on thelong-wavelength side is, for example, in a range of 500 nm to 515 nm.

In other words, in the brightness priority mode according to theembodiment, all the green component light G and thelong/short-wavelength component light LS are used as shown in FIG. 4. Onthe other hand, in the color reproducibility priority mode according tothe embodiment, the long/short-wavelength component light LS is cut offand thus only the green component light G is used as shown in FIG. 5. Inthe color reproducibility priority mode, the lower limit of thewavelength band of the green component light G is in a range of 500 nmto 515 nm, while the upper limit of the wavelength band of the greencomponent light G is in a range of 565 nm to 580 nm.

As described above, in the brightness priority mode according to theembodiment, brightness can be secured in the same level as theconventional technique (2). Note that, in the brightness priority modeaccording to the embodiment, it is a matter of course that brightnesscan be secured in a higher level than the conventional technique (1).

Meanwhile, in the color reproducibility priority mode according to theembodiment, the DM2 shifts to the long-wavelength side, so that thepurity of red reproduced by the red component light R is higher thanthose of the conventional technique (1) and the conventional technique(2). In the color reproducibility priority mode according to theembodiment, the long-wavelength component light Gl and theshort-wavelength component light Gs are cut off, so that the purity ofgreen reproduced by the green component light G is higher than those ofthe conventional technique (1) and the conventional technique (2). Inthe color reproducibility priority mode according to the embodiment, theshort-wavelength component light Gs is cut off in addition to thelong-waves component light Gl, so that green reproduced by the greencomponent light G can be prevented from shifting to the blue side.

(Configuration of Polarization-State Adjusting Element)

Hereinbelow, a mechanism for improving green color purity and red colorpurity in the color reproducibility priority mode will be described.Specifically, a configuration of the polarization-state adjustingelement according to the embodiment will be described with reference tothe drawings. FIG. 6 is a diagram showing a schematic configuration nearthe polarization-state adjusting element 51X according to the firstembodiment.

As shown in FIG. 6, the long/short-wavelength component light LS, i.e.the long-wavelength component light Gl and the short-wavelengthcomponent light Gs, is reflected by the dichroic minor 72. Similarly,the central-wavelength component light Gc is reflected by the dichroicmirror 72. Thus, the central-wavelength component light Gc and thelong/short-wavelength component light LS are guided to thepolarization-state adjusting element 51X.

Here, when the polarization state of the long/short-wavelength componentlight LS is adjusted by the polarization-state adjusting element 51X,the long/short-wavelength component light LS is shielded by thelight-incident-side polarizing plate 52G. Here, when the polarizationstate of the long/short-wavelength component light LS is not adjusted bythe polarization-state adjusting element SIX, the long/short-wavelengthcomponent light LS is transmitted through the light-incident-sidepolarizing plate 52G.

As shown in FIG. 7A, in an LS-ON state, the polarization-state adjustingelement 51X transmits the long/short-wavelength component light LSwithout adjusting the polarization state of the long/short-wavelengthcomponent light LS. In other words, on the light-emitting-side of thepolarization-state adjusting element 51X, the polarization state of thelong/short-wavelength component light LS is the same as the polarizationstate of the central-wavelength component light Gc. The LS-ON state is astate where the long/short-wavelength component light LS is used.

As shown in FIG. 7B, in an LS-OFF state, the polarization-stateadjusting element 51X transmits the long/short-wavelength componentlight LS while adjusting the polarization state of thelong/short-wavelength component light LS. In other words, on thelight-emitting-side of the polarization-state adjusting element 51X, thepolarization state of the long/short-wavelength component light LS isdifferent from the polarization state of the central-wavelengthcomponent light Gc. The LS-OFF state is a state where thelong/short-wavelength component light LS is not used.

Note that, the present embodiment is described on the assumption thatthe LS-ON state is a state where no voltage is applied to thepolarization-state adjusting element 51X (POWER OFF); however, theLS-OFF state includes a state where a low voltage is applied to thepolarization-state adjusting element 51X (a low-voltage applicationstate).

Note that, the present embodiment is described on the assumption thatthe LS-OFF state is a state where a voltage is applied to thepolarization-state adjusting element 51X (POWER ON); however, the LS-ONstate includes a state where a high voltage is applied to thepolarization-state adjusting element 51X (a high-voltage applicationstate).

As shown in FIGS. 7A and 7B, the amount of the long/short-wavelengthcomponent light LS reaching the cross dichroic prism 60 is controlled bywitching between the LS-ON state and the LS-OFF state. In other words,the polarization-state adjusting element 51X adjusts the polarizationstate of the long/short-wavelength component light LS, so that the modeis switched between the mode with priority given to colorreproducibility (the color reproducibility priority mode) and the modewith priority given to brightness (the brightness priority mode).

Hereinbelow, a case where an edge filter element is used as thepolarization-state adjusting element 51X will be described FIG. 8 is adiagram for explaining the edge filter element according to the firstembodiment.

As shown in FIG. 8, the polarization-state adjusting element 51X of theedge filter type does not adjust (rotate) the polarization direction ofeither of color component light beams (the central-wavelength componentlight Gc and the long/short-wavelength component light LS), in a statewhere no voltage is applied to the polarization-state adjusting element51X (OFF state).

Meanwhile, the polarization-state adjusting element 51X of the edgefilter type adjusts (rotates) the polarization direction of thelong/short-wavelength component light LS (the long-wavelength componentlight Gl and the short-wavelength component light Gs) but does notadjust (rotate) the polarization direction of the central-wavelengthcomponent light Gc, in a state where a voltage is applied to thepolarization-state adjusting element 51X (ON state).

Note that, FIG. 8 shows a ratio (transmittance) in which each of thecolor component light beams is transmitted through thepolarization-state adjusting element 51X of the edge filter type withthe polarization direction thereof is not adjusted (rotated) when thecolor component light beam is incident on the polarization-stateadjusting element 51X of the edge filter type. Accordingly, it should benoted that, in FIG. 8, the polarization direction of each colorcomponent light beam is adjusted rotated) to a greater extent as thetransmittance becomes lower.

(Function of Polarization-State Adjusting Element)

Hereinbelow, the function of the polarization-state adjusting elementaccording to the first embodiment will be described with reference tothe drawing. FIG. 9 is a diagram for explaining the function of thepolarization-state adjusting element 51X according to the firstembodiment.

FIG. 9 shows a combination of the polarization-state adjusting element51X and the light-incident-side polarizing plate 52G. Apolarization-state adjusting element 51X-1 is an element which adjusts(rotates) only the polarization direction of the long/short-wavelengthcomponent light LS (the long-wavelength component light Gl and theshort-wavelength component light Gs) by 90° when a voltage is appliedthereto (POWER ON). Meanwhile, a polarization-state adjusting element51X-2 is an element which adjusts (rotates) only the polarizationdirection of the long/short-wavelength component light LS by 90° when novoltage is applied thereto (POWER OFF).

A light-incident-side polarizing plate 52G-1 is an element whichtransmits light having P-polarization but shields light havingS-polarization. The light-incident-side polarizing plate 52G-1 is used,for example, when light emitted by the light source 10 is uniformlyconverted into P-polarization. Meanwhile, a light-incident-sidepolarizing plate 52G-2 is an element which transmits light havingS-polarization but shields light having P-polarization. Thelight-incident-side polarizing plate 52G-2 is used, for example, whenlight emitted by the light source 10 is uniformly converted intoS-polarization.

Firstly, consider that the polarization-state adjusting element 51X-1 isused when light emitted by the light source 10 is uniformly convertedinto P-polarization. In this case, the amount of thelong/short-wavelength component light LS reaching the cross dichroicprism 60 becomes the maximum when no voltage is applied to thepolarization-state adjusting element 51X-1 (POWER OFF). Note that, whena voltage is applied to the polarization-state adjusting element 51X-1(POWER ON), the polarization direction of the long/short-wavelengthcomponent light LS (S-polarization) is different from the polarizationdirection of the central-wavelength component light Gc (P-polarization).For this reason, the long/short-wavelength component light LS havingS-polarization is shielded by the light-incident-side polarizing plate52G-1.

Secondly, consider that the polarization-state adjusting element 51X-2is used when light emitted by the light source 10 is uniformly convertedinto P-polarization. In this case, the amount of thelong/short-wavelength component light LS reaching the cross dichroicprism 60 becomes the maximum when a voltage is applied to thepolarization-state adjusting element 51X-2 (POWER ON). Note that, whenno voltage is applied to the polarization-state adjusting element 51X-2(POWER OFF), the polarization direction of the long/short-wavelengthcomponent light LS (S-polarization) is different from the polarizationdirection of the central-wavelength component light Gc (P-polarization).For this reason, the long/short-wavelength component light LS havingS-polarization is shielded by the light-incident-side polarizing plate52G-1.

Thirdly, consider that the polarization-state adjusting element 51X-1 isused when light emitted by the light source 10 is uniformly convertedinto S-polarization. In this case, the amount of thelong/short-wavelength component light LS reaching the cross dichroicprism 60 becomes the maximum when no voltage is applied to thepolarization-state adjusting element 51X-1 (POWER OFF). Note that, whena voltage is applied to the polarization-state adjusting element 51X-1(POWER ON), the polarization direction of the long/short-wavelengthcomponent light LS (P-polarization) is different from the polarizationdirection of the central-wavelength component light Gc (S-polarization).For this reason, the long/short-wavelength component light LS havingP-polarization is shielded by the light-incident-side polarizing plate52G-2.

Fourthly, consider that the polarization-state adjusting element 51X-2is used when light emitted by the light source 10 is uniformly convertedinto S-polarization. In this case, the amount of thelong/short-wavelength component light LS reaching the cross dichroicprism 60 becomes the maximum when a voltage is applied to thepolarization-state adjusting element 51X-2 (POWER ON). Note that, whenno voltage is applied to the polarization-state adjusting element 51X-2(POWER OFF), the polarization direction of the long/short-wavelengthcomponent light LS (P-polarization) is different from the polarizationdirection of the central-wavelength component light Gc (S-polarization).For this reason, the long/short-wavelength component light LS havingP-polarization is shielded by the light-incident-side polarizing plate52G-2.

(Function of Projection Display Apparatus)

Hereinbelow, the function of the projection display apparatus accordingto the first embodiment will be described with reference to the drawing.FIG. 10 is a block diagram showing the function of the projectiondisplay apparatus 100 according to the first embodiment.

As shown in FIG. 10, the projection display apparatus 100 includes acontroller 200. The controller 200 includes a signal receiver 210, amode setter 220, and a modulation amount controller 230.

The signal receiver 210 receives color signals (a first input signal(hereinafter, referred to as R signal), a second input signal(hereinafter, referred to as G signal), and a third input signal(hereinafter, referred to as B signal)). For example, the signalreceiver 210 acquires the color signals from a color separation sectionconfigured to separate a color signal from an image signal.

The mode setter 220 controls the mode with priority given to colorreproducibility (color reproducibility priority mode) or the mode withpriority given to brightness brightness priority mode). Specifically,the mode setter 220 controls whether or not the polarization directionof the long/short-wavelength component light LS (the long-wavelengthcomponent light Gl and the short-wavelength component light Gs) isadjusted (rotated) by the polarization-state adjusting element 51X.

The modulation amount controller 230 controls an amount of modulation ofeach liquid crystal panel 50 (the liquid crystal panel 50R, the liquidcrystal panel 50G, and the liquid crystal panel 50B), based on the Rsignal, the G signal, and the B signal acquired from the signal receiver210. In addition, the modulation amount controller 230 controls anamount of modulation of the polarization-state adjusting element 51X.

Specifically, the modulation amount controller 280 inputs the R signalinto the liquid crystal panel 50R. Similarly, the modulation amountcontroller 230 inputs the G signal into the liquid crystal panel 50G.Likewise, the modulation amount controller 230 inputs the B signal intothe liquid crystal panel 50B.

The modulation amount controller 230 generates an LS signal forcontrolling the long/short-wavelength component light LS, and inputs theLS signal into the polarization-state adjusting element 51X.Specifically, when the color reproducibility priority mode is selected,the modulation amount controller 230 inputs an LS signal which adjuststhe polarization state of the long/short-wavelength component light LSto obtain an LS-OFF state into the polarization-state adjusting element51X. When the brightness priority mode is selected, the modulationamount controller 230 inputs an LS signal which adjusts the polarizationstate of the long/short-wavelength component light LS to obtain an LS-ONstate into the polarization-state adjusting element 51X.

(Wavelength Band of Each of Color Component Light Beams)

Hereinbelow, the wavelength band of each of color component light beamsaccording to the first embodiment will be described with reference tothe drawing. FIG. 11 is a diagram showing the wavelength band of eachcolor component light beam according to the first embodiment.

As shown in FIG. 11, the red component light R is the light (the firstcolor component light) having at least a red wavelength band (the firstwavelength band). In the first embodiment, the red component light R hasa wavelength band on the longer wavelength side than a wavelength bandof a long-wavelength-side intermediate color having a hue between greenand red. The long-wavelength-side intermediate color is, for example,yellow and orange.

The blue component light B is the light (the third color componentlight) having at least a blue wavelength band (the third wavelengthband). In the first embodiment, the blue component light B has awavelength band on the shorter wavelength side than a wavelength band ofa short-wavelength-side intermediate color having a hue between blue andgreen. The short-wavelength-side intermediate color is, for example, apart of cyan (on the long-wavelength side).

The green component light G is the light (the second color componentlight) at least having a green wavelength band (a second wavelengthband). In the first embodiment, the green component light G has awavelength band on the longer wavelength side than the wavelength bandof the short-wavelength-side intermediate color. The green componentlight G has a wavelength band on the shorter wavelength side than thewavelength band of the long-wavelength-side intermediate color.

As described above, the green component light G includes thecentral-wavelength component light Gc, the short-wavelength componentlight Gs, and the long-wavelength component light Gl. In the firstembodiment, the long-wavelength component light Gl has the wavelengthband of the long-wavelength-side intermediate color (for example, yellowand orange). The short-wavelength component light Gs has the wavelengthband of the short-wavelength-side intermediate color or example, a part(on the long-wavelength side) of cyan).

The amount of light emitted by the light source 10 is the product ofluminosity function of the light emitted by the light source 10 andenergy generated by the light source 10. The amount of light emitted bythe light source 10 has a peak in the wavelength band of green and inthe wavelength band of yellow.

The luminosity function of the light emitted by the light source 10 isthe ratio (relative value) of sensitivity for each wavelength to thehighest sensitivity, where energy of light emitted by the light source10 is the same. The luminosity function of the light emitted by thelight source 10 has the peak at the wavelength band of green, anddecreases as the wavelength increases from the wavelength band of greento the longer wavelength side (or, decreases to the shorter wavelengthside).

As can be seen from the characteristics of the light emitted by thelight source 10, light having a yellow wavelength band is preferablyused to improve brightness of an image projected onto a screen (notillustrated) or the like, in addition to light having a red wavelengthband, light having a green wavelength band, and light having a bluewavelength band.

Here, a cutoff wavelength of the dichroic mirror 71 configured toseparate the blue component light B from the other color componentlights is provided on the shorter wavelength side than the wavelengthband of the short-wavelength-side intermediate color. The cutoffwavelength of the dichroic mirror 71 is, for example, in a range ofabout 495 nm to 510 nm.

Meanwhile, a cutoff wavelength of the dichroic mirror 72 configured toseparate the red component light R from another color component light isprovided on the longer wavelength side than the wavelength band of thelong-wavelength-side intermediate color. The cutoff wavelength of thedichroic mirror 72 is, for example, in a range of about 595 nm to 605nm.

In the first embodiment, the cutoff wavelength of the dichroic mirror isprovided on the longer wavelength side than that of the conventionaltechnique. Thus, the purity of red reproduced by the red component lightR is improved. Meanwhile, in the brightness priority mode, brightness ofan image projected onto a screen can be improved because thelong-wavelength component light Gl including light having a wavelengthband of yellow or orange.

In the first embodiment, in the color reproducibility priority mode, thepurity of green reproduced by the green component light G (that is, thecentral-wavelength component light Gc) is improved because theshort-wavelength component light Gs and the long-wavelength componentlight Gl are cut off.

(Comparison of Color Reproduction Range)

Hereinbelow, the color reproduction range according to the conventionaltechnique and the color reproduction range according to the embodimentwill be compared with each other. Specifically, the comparison betweenthe color reproduction range according to the above-mentionedconventional technique (2) and the color reproduction range according tothe embodiment will be described with reference to FIG. 12.

As shown in FIG. 12, in the color reproducibility priority modeaccording to the conventional technique (2), only the yellow componentlight Ye is cut off by the selective superimposing optical element.Meanwhile, in the color reproducibility priority mode according to theembodiment, the long-wavelength component light Gl and theshort-wavelength component light Gs are cut off by thepolarization-state adjusting element.

Accordingly, in the color reproducibility priority mode (LS-OFF)according to the embodiment, green reproduced by the green componentlight G is prevented from shifting to the blue side, as compared withthe conventional technique (2). In other words, in the colorreproducibility priority mode according to the embodiment, the purity ofgreen reproduced by the green component light G is higher than that ofthe conventional technique (2).

In the color reproducibility priority mode according to the embodiment,the DM2 is provided on the longer wavelength side than the conventionaltechnique (2). Accordingly, in the color reproducibility priority modeaccording to the embodiment, the purity of red reproduced by the redcomponent light R is higher than that of the conventional technique (2).

As described above, in the color reproducibility priority mode (LS-OFF)according to the embodiment, the purities of green and red are higherthan those of the conventional technique (2), so that the colorreproduction range expands properly.

Note that, in the brightness priority mode according to the embodiment(LS-ON), light emitted by the light source is effectively used in thesame manner as in the conventional technique (2). Accordingly, in thebrightness priority mode according to the embodiment, brightness can besecured in the same level as that of the conventional technique (2).

(Advantages and Effects)

In the first embodiment, the green component light G emitted from thepolarization-state adjusting element 51X is incident on the liquidcrystal panel 50G or the green component light G. In other words, thereare three types of light incident on the cross dichroic prim 60. As aresult, the design of the projection lens unit 110 need not be changedand thus an increase in cost of the entire apparatus can be suppressed.

In the first embodiment, the polarization-state adjusting element 51Xseparately adjusts the polarization state of the central-wavelengthcomponent light Gc and the polarization state of thelong/short-wavelength component light LS (the long-wavelength componentlight Gl and the short-wavelength component light Gs). Specifically, thepolarization-state adjusting element 51X transmits thecentral-wavelength component light Gc without adjusting the polarizationstate of the central-wavelength component light Gc. Meanwhile, thepolarization-state adjusting element 51X transmits thelong/short-wavelength component light LS (the long-wavelength componentlight Gl and the short-wavelength component light Gs) while adjustingthe polarization state of the long/short-wavelength component light LS.Accordingly, the mode with priority given to color reproducibility(color reproducibility priority mode) and the mode with priority givento brightness (brightness priority mode) can be switched from one to theother.

In the first embodiment, in the color reproducibility priority mode, thepurity of green reproduced by the green component light G (thecentral-wavelength component light Gc) is improved by cutting off thelong/short-wavelength component light LS (the long-wavelength componentlight Gl and the short-wavelength component light Gs) from the greencomponent light G. Meanwhile, in the brightness priority mode, theamount of light guided to the cross dichroic prism 60 is increasedbecause the long/short-wavelength component light LS (thelong-wavelength component light Gl and the short-wavelength componentlight Gs) is included in the green component light G.

In the first embodiment, the long-wavelength component light Gl has thewavelength band of the long-wavelength-side intermediate color orexample, yellow and orange). In other words, the red component light Rhas a wavelength band on the longer wavelength side than the wavelengthband of the long-wavelength-side intermediate color. As described above,see the red component light R includes no wavelength band of thelong-wavelength-side intermediate color (particularly, orange), thepurity of red reproduced by the red component light R is improved.

In the first embodiment, the short-wavelength component light Gs has thewavelength band of the short-wavelength-side intermediate color orexample, a part of cyan). In other words, the blue component light B hasa wavelength band on the longer wavelength side than the wavelength bandof the short-wavelength-side intermediate color. As described above,since the blue component light B includes no wavelength band of theshort-wavelength-side intermediate color, the purity of blue reproducedby the blue component light B is improved.

In the first embodiment, the long-wavelength component light Gl includesthe wavelength band of the long-wavelength-side intermediate color(particularly, orange). Meanwhile, in the color reproducibility prioritymode, the long-wavelength component light Gl is cut off. Here, in thecolor reproducibility priority mode, green reproduced by the greencomponent light G can be prevented from shifting to the blue side bycutting off the short-wavelength component light Gs in addition to thelong-wavelength component light Gl.

[Second Embodiment]

Hereinbelow, a projection display apparatus according to a secondembodiment will be described with reference to the drawings. It shouldbe noted that differences between the above-mentioned first embodimentand the second embodiment will be main described

Specifically, in the first embodiment, the polarization-state adjustingelement 51X is an edge filter element. In contrast, in the secondembodiment, the polarization-state adjusting element 51X is a notchfilter element.

(Configuration of Polarization-State Adjusting Element)

Hereinbelow, a case where a notch filter element is used as thepolarization-state adjusting element 51X according to the secondembodiment will be described with reference to the drawing. FIG. 13 is adiagram showing a schematic configuration near the polarization-stateadjusting element 51X according to the second embodiment.

As shown in FIG. 13, the notch-filter-type polarization-state adjustingelement 51X is located between the condenser lens 83G and thelight-incident-side polarizing plate 52G, and is provided by laminatingtwo plates on an optical path of the green component light G (thecentral-wavelength component light Gc and the long/short-wavelengthcomponent light LS) separated by the dichroic mirror 72.

Specifically, the notch-filter-type polarization-state adjusting element51X is formed of a light-incident-side polarization-state adjustingelement 51X-A and a light-emitting-side polarization-state adjustingelement 51X-B.

For example, the light-incident-side polarization-state adjustingelement 51X-A does not adjust the central-wavelength component light Gc,but adjusts only the polarization state of the long-wavelength componentlight Gl having the wavelength band of the long-wavelength-sideintermediate color (for example, yellow and or ). Meanwhile, thelight-emitting-side polarization-state adding element 51X-B does notadjust the central-wavelength component light Gc, but adjusts only thepolarization state of the short-wavelength component light Gs having thewavelength band of the short-wavelength-side intermediate color orexample, a part of cyan (on the long-wavelength side)).

(Function of Polarization-State Adjusting Element)

Hereinbelow, the functions of the light-incident-side polarization-stateadjusting element 51X-A and light-emitting-side polarization-stateadjusting element 51X-B according to the second embodiment will bedescribed with reference to the drawings. FIGS. 14A and 14B are diagramseach for explaining the function of the notch filter element accordingto the second embodiment.

As shown in FIG. 14A, when no voltage is applied to thelight-incident-side polarization-state adjusting element 51X-A (POWEROFF), the light-incident-side polarization-state adjusting element 51X-Atransmits the green component light G without rotating the polarizationdirection of the long-wavelength component light Gl.

Meanwhile, when a voltage is applied to the light-incident-sidepolarization-state adjusting element 51X-A (POWER ON), thelight-incident-side polarization-state adjusting element 51X-A transmitsthe green component light G while rotating only the polarizationdirection of the long-wavelength component light Gl.

As shown in FIG. 14B, when no voltage is applied to thelight-emitting-side polarization-state adjusting element 51X-B (POWEROFF), the light-emitting-side polarization-state adjusting element 51X-Btraits the green component light G without rotating the polarizationdirection of the short-wavelength component light Gs.

Meanwhile, when a voltage is applied to the light-emitting-sidepolarization-state adjusting element 51X-B (POWER ON), thelight-emitting-side polarization-state adjusting element 51X-B transmitsthe green component light G while rotating only the polarizationdirection of the short-wavelength component light Gs.

(Advantages and Effects)

In the projection display apparatus 100 according to the secondembodiment, the light-incident-side polarization-state adjusting element51X-A and the light-emitting-side polarization-state adjusting element51X-B are laminated when using the notch-filter-type polarization-stateadjusting element 51X. Accordingly, the projection display apparatus 100is capable of separately adjusting the polarization state of thecentral-wavelength component light Gc and each of the polarizationstates of the long-wavelength component light Gl and theshort-wavelength component light Gs. Thus, the same effects as those inthe first embodiment can be obtained.

[Third Embodiment]

Hereinbelow, a third embodiment will be described with reference to thedrawing. In the third embodiment, the configuration of theabove-mentioned liquid crystal panel 50 will be described in detail.

(Configuration of Light Valve)

Hereinbelow, the configuration of a light valve in the third embodimentwill be described with reference to the drawing. FIG. 15 is a diagramshowing the configuration of the liquid crystal panel 50 (particularly,the polarization-state adjusting element 51X and the like) in the thirdembodiment. Note that, FIG. 15 is a diagram of the liquid crystal panel50 viewed from a light-incident surface (or a light-emitting surface)side of the liquid crystal panel 50.

As shown in FIG. 15, the liquid crystal panel 50 includes multiplesegments 310 and multiple transparent electrodes 320.

The segments 310 are arranged in a matrix, and can be taken as havingfour regions (regions A to D).

In the regions provided in the upper half of the liquid crystal panel 50(the region A and the region B), the area of each segment 310 decreasesas the position level of the segment 310 goes up. Meanwhile, in theregions provided in the lower half of the liquid crystal panel 50 (theregion C and the region D), the area of each segment 310 decreases asthe position level of the segment 310 goes down.

Meanwhile, in the regions provided in the left half of the liquidcrystal panel 50 (the region A and the region D), the transparentelectrode 320 is provided on the left side of each of the segments 310.In the regions provided in the right half of the liquid crystal panel 50(the region B and the region C), the transparent electrode 820 isprovided on the right side of each of the segments 310.

Here, the configuration of each segment 310 will be further described indetail by giving segments 311 to 314 as examples.

The area of the segment 312 provided on the upper side of the segment311 is smaller than the area of the segment 311 by the width of atransparent electrode 321 connected to the segment 311.

The area of the segment 313 provided on the upper side of the segment312 is further smaller than the area of the segment 312 by the width ofa transparent electrode 322 connected to the segment 312. In otherwords, the area of the segment 313 is smaller than the area of thesegment 311 by the widths of the transparent electrodes 321 and 322.

The area of the segment 314 provided on the upper side of the segment313 is further smaller than the area of the segment 813 by the width ofa transparent electrode 328 connected to the segment 313. In otherwords, the area of the segment 314 is smaller than the area of thesegment 311 by the widths of the transparent electrodes 321 to 323.

Each of the transparent electrodes 320 is formed of a transparentmember, and is connected to a corresponding one of the segments 310. Inaddition, the transparent electrodes 320 are provided in spaces formedby reduction of the areas of the segments 310.

In the regions provided in the upper half of the liquid crystal panel 50(the region A and the region B), the transparent electrodes 820 areconnected to a flexible printed circuit (FPC) (not illustrated) providedabove the liquid crystal panel 50. In the regions provided in the lowerhalf of the liquid crystal panel 50 (the region C and the region D), thetransparent electrodes 320 are connected to an FPC (not illustrated)provided below the liquid crystal panel 50.

It should be noted that, in the third embodiment, an example is given ofa case where the FPCs are provided above and below the liquid crystalpanel 50; however, the present invention is not limited to this case.Specifically, the FPCs may be provided to the right and the left of theliquid crystal panel 50. In this case, it is of course sufficient thatthe configuration shown in FIG. 15 only needs to be turned by 90°.

(Advantages and Effects)

When it is unfavorable to route the transparent electrodes 320 in athickness direction of the liquid crystal panel 50, that is, when it isunfavorable to route the transparent electrodes 320 in thelight-incident surface (the light-emitting surface), the liquid crystalpanel 50 according to the third embodiment is capable of efficientlyreducing the spaces in which the transparent electrodes 320 areprovided. In other words, the proportion of area where each segment 310occupies in the liquid crystal panel 50 is increased, and therebyeffects of modulation by each segment 310 can be sufficiently obtained.

Using the transparent electrodes 320 as electrodes connectedrespectively to the segments 310 sufficiently suppresses reduction inlight use efficiency attributable to the electrodes.

Since the FPCs are provided above and below the liquid crystal panel 50,the length of each transparent electrode 320 can be reduced. For thisreason, the electrical resistance of each transparent electrode 320 isreduced, and thereby the width of the transparent electrode 320 can bereduced.

[Other Embodiments]

Although the present invention has been described with theabove-mentioned embodiments, it should be understood that thedescription and drawings constituting a part of this disclosure do notlimit the present invention. Various alternative embodiments, examples,and operation techniques will be apparent from this disclosure to thoseskilled in the art.

Specifically, in the above-mentioned embodiments, a superimposingcomponent light is the green component light G, and thelong/short-wavelength component light LS is the long-wavelengthcomponent light Gl and short-wavelength component light Gs; however, thepresent invention is not limited to this configuration. For example, thesuperimposing component light may be the blue component light B, and insuch a case, the fourth color component light may be theshort-wavelength component light Gs or the like.

Although not specifically described in the first embodiment, when thepolarization-state adjusting element 51X adjusts the polarization stateof the long-wavelength component light Gl, an amount of modulation mayof course be controlled in accordance with an input signal for red, aninput signal for green, and an input signal for blue.

In this case, the polarization state of the long-wavelength componentlight Gl is adjusted in accordance with whether or not a voltage isapplied to the polarization-state adjusting element 51X (POWER ON orPOWER OFF). In other words, the polarization-state adjusting element 51Xis an optical element that adjusts an amount of modulation of along-wavelength component light Gl to be superimposed on the greencomponent light G, which is to be applied to the liquid crystal panel50G.

Specifically, the modulation amount controller 230 calculates arepresentative value of brightness on the basis of the input signal forred, the input signal for green, and the input signal for blue. Therepresentative value of brightness is, for example, a minimum value ofbrightness, a maximum value of brightness, an average value ofbrightness, or the like. Subsequently, the modulation amount controller230 determines an amount of superimposition of the long-wavelengthcomponent light Gl with respect to an image in accordance with therepresentative value of brightness, and thereby controls the amount ofmodulation of the polarization-state adding element 51X.

In the above-mentioned embodiments, the case where orange is used as theintermediate color between yellow and red has been described; however,the present invention is not limited to this case. It is a matter ofcourse that the present invention only needs to have a wavelength bandbetween yellow and red.

In the above-mentioned embodiments, each of the liquid crystal panels 50(the liquid crystal panel 50R, the liquid crystal panel 50G, and theliquid crystal panel 50B) is provided with a compensator; however, thepresent invention is not limited to this configuration. The compensatoris not necessarily provided.

Various alternative embodiments, examples, and operational techniqueswill become apparent from this disclosure to those skilled in the art.Thus, the technical scope of the present invention is only defined bythe subject matters according to the scope of claims appropriate fromthe foregoing description.

1. An illumination apparatus comprising: a light source configured toemit white light; a color separator configured to separate the whitelight emitted by the light source into a first color component lighthaving a first wavelength band, a second color component light having asecond wavelength band, and a third color component light having a thirdwavelength band; a first light valve configured to modulate the firstcolor component light on the basis of a first input signal; a secondlight valve configured to modulate the second color component light onthe basis of a second input signal; a third light valve configured tomodulate the third color component light on the basis of a third inputsignal; a color combiner configured to combine the first color componentlight emitted from the first light valve, the second color componentlight emitted from the second light valve, and the third color componentlight emitted from the third light valve; and a polarization-stateadjusting element provided on the light-incident-side of the secondlight valve, wherein the second wavelength band has a central-wavelengthband, a short-wavelength band on the shorter wavelength side than thecentral-wavelength band, and a long-wavelength band on the longerwavelength side than the central-wavelength band, and thepolarization-state adjusting element is configured to separately adjusta polarization state of light in the central-wavelength band and apolarization state of light in each of the short-wavelength band and thelong-wavelength band.
 2. The illumination apparatus according to claim1, wherein the long-wavelength band has a wavelength band wider than awavelength band of the short-wavelength band.
 3. The illuminationapparatus according to claim 1, wherein the polarization-state adjustingelement is an edge filter element configured not to adjust thepolarization state of light in the central-wavelength band but to adjustthe polarization state of light in each of the short-wavelength band andthe long-wavelength band.
 4. The illumination apparatus according toclaim 1, wherein the polarization-state adjusting element is formed of acombination of: a first notch filter element configured not to adjustthe polarization state of light in the central-wavelength band but toadjust the polarization state of light in the short-wavelength band; anda second notch filter element configured not to adjust the polarizationstate of light in the central-wavelength band but to adjust thepolarization state of light in the long-wavelength band.
 5. Theillumination apparatus according to claim 1, wherein the secondwavelength band includes at least a green wavelength band.
 6. Aprojection display apparatus comprising: a light source configured toemit white light; a color separator configured to separate the whitelight emitted by the light source into a first color component lighthaving a first wavelength band, a second color component light having asecond wavelength band, and a third color component light having a thirdwavelength band; a first light valve figured to modulate the first colorcomponent light on the basis of a first input signal; a second lightvalve configured to modulate the second color component light on thebasis of a second input signal; a third light valve configured tomodulate the third color component light on the bas of a third inputsignal; a color combiner configured to combine the first color componentlight emitted from the first light valve, the second color componentlight emitted from the second light valve, and the third color componentlight emitted from the third light valve; projection means configured toproject light emitted from the color combiner; and a polarization-stateadjusting element provided on the light-incident-side of the secondlight valve, wherein the second wavelength band has a central-wavelengthband, a short-wavelength band n the shorter wavelength side than thecentral-wavelength band, and a long-wavelength band on the longerwavelength side than the central-wavelength band, and thepolarization-state adjusting element is configured to separately adjusta polarization state of light in the central-wavelength band and apolarization state of light in each of the short-wavelength band and thelong-wavelength band.